218 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



wheel and therewith respecting the meridian (by providing 

 a meridian Hne or azimuth Une through the borehole). 

 Thus we get the lateral angle aboveground. The damping 

 of the circle is easily obtained by chambers between which 

 some oil runs in and out on the oscillations of 

 the wheel axis. 



Above in the steel shell comes the plumbing 

 device (Fig. 151). The rigid plumb bob a 

 hangs by Cardan suspension in a guide and is 

 prolonged in a rod b as far above as it hangs 

 below. The plummet carries above and below 

 a small contact bead or ball. Each of these 

 two balls runs in a slit between contact tracts 

 c and d on a lateral support capable of tipping 

 e and /. In space the slits stand at right 

 angles to one another. The upper support turns 

 about an axis which is in a position at right 

 angles to that of the lower one. The inclina- 

 tion is resolved into two components at right 

 angles to one another. Naturally the same 

 action can be obtained as well by two sepa- 

 rate pendulums. When the contact balls fit 

 laterally into their slits the current is cut off and 

 the parts concerned will be so far displaced 

 laterally that no further side contact can take 

 place until the rigid plummet hangs free. The 

 contact chariot of the transmitter is, however, 

 connected to the corresponding parts of the 

 receiver by means of the electrical conductor in the cable. 

 As long as the transmitter parts are in lateral motion 

 the current to the receiver is cut off and it there displaces a 

 motor contact carriage in the same manner. Both compo- 

 nents are compounded in the receiver yielding the total 

 motion of a magnet bar whose deviation from a mean 

 position is shown on the concentric rings of a graduated 

 plate by means of a small iron ball on a rod which moves 

 according to the magnitude of the inclination of the bore- 



FiG. 151.— 

 Anschiitz ap- 

 paratus. The 

 plumbing de- 

 vice. 



